Invoking services that don't require XML Input (An example please)

Hi,

I've been trying to follow the AJAX tutorial to invoke a service through Firefox that I had earlier deployed on Mashup Server. This is a simple service in "$MASHUP_HOME/scripts/admin/groceryList.js" whose code is as follows: 

function getList()
{
    var a = new XML();

    a = <order/>;
    var b = <line-item prod="tomato" qty="4"/>;
    var c = <line-item prod="potato" qty="3"/>;
    var d = <line-item prod="onion" qty="6"/>;
    var e = <line-item prod="chilli" qty="40"/>;

    a.appendChild(b);
    a.appendChild(c);
    a.appendChild(d);
    a.appendChild(e);

    return <response>{a}</response>;
}

This service does not require any XML input. How should I invoke it? The user guide (http://wso2.org/projects/wsf/ajax/xpi/0.1/docs/userguide.html) only has the XML In/XML Out example. I tried a few variations on the example code but nothing worked. (The XPI is correctly installed, and I've verified it by running the test code provided in the user guide.)

Regards,

Ganesh